The primary design tool in my digital collage tool box is the Diana photo app. Pretty sure it’s free. It allows you to select two photos and then double exposes them with a variety of filters.

[My other heavy hitters are PicFrame — for making mosaics — and Hipstamatic — a photo app that applies a filter and a frame as you shoot. Many of the photos that I double expose through Dianaphoto were shot in Hipstamatic.]

This post will give you the basic skills to use the Diana Photo app. It is a ton of fun, addictive even. Don’t say I didn’t warn you!

First, select two pictures by tapping the camera icons in the squares at bottom. The app automatically applies one of its filters. I’ll show you how to select a different filter in a minute.

• Tip. If you’re like me and have 1,000’s of photos on your phone, you might want to create an album before starting. That can spare you a lot of scrolling.

If you find yourself intrigued by one of the two selected photos and want to keep it in place while changing out the other, lock it in place by depressing your finger slightly on the picture itself.

A lock icon will show up

Locking a picture allows you to audition how it will look with different pictures or filters or both. To unlock, simply hold your finger down on the locked image.

Next, select a filter. There are a couple of dozen. The variability of effect includes not just color and intensity, but also which parts of the photos are visible. Note that there is also a “no filter” option.

To select another filter, you can swipe left on the double exposure (without the filter grid visible) and whatever filter comes next in the app will be applied. In the alternative, you can hold your finger down on the double exposure and the black filter grid-menu will appear. Then tap to select. This latter method is efficient if you know your favorite filters. There are quite a number of filters that I never use.

To save the double exposure, simply tap the three connected circles ICON at the upper left. That will produce a menu for you to select where to put the pic. I always save to my camera roll, even if it will later go on Instagram or FB or wherever.

Below, find the same two photos with different filters. It gives you an idea of the kinds of changes produced by the app.

Directly below the double exposure, there’s a white dot flanked by plus and minus signs. An intensity slider. Hold lightly and slide left or right to dim or heighten the double exposure. I wish this feature was more interesting. A lost opportunity, IMHO.

Above left shows a fully dimmed filter while the right shows the button slid all the way to the right.

Another design tool is the swap. The selected pictures at bottom can be switched left/right by swiping left or right. This may produce radically different filter results (note, sometimes it makes little to no difference).

Dianaphotoapp has two ways of letting you make random selections. You can tap the dice at upper left and if no photo had been locked, it will select two photos from your camera roll. If you’ve locked an image, then it’ll only select one. I’ve read you can shake your phone too, something I’ve yet to try.

I love the dice function. Absolutely love it.

By using photos of collage or quilts, these pix gain a little artistry (IMHO). Also, when one or both picture is ALREADY a double exposure, some really quirky mysterious effects can be achieved.

That’s one reason why I use the hashtag #lostcountoftheexposures over on Instagram. I also always use #dianaphoto and #dianaphotoapp so that others having fun with this app can see.

Also, once in a while, the official Diana app account will feature one of my pix (last photo, below).

Have fun! Trust me, it’s a super easy app to use.